Games like 666: El día del portal
Games like 666: El día del portal include Broforce, Teenage Mutant Ninja Turtles: Shredder's Revenge, Warhammer 40,000: Boltgun, BlazBlue Entropy Effect, and METAL SLUG. We matched them by the tags players give 666: El día del portal on Steam (Action, Action-Adventure, Point & Click, Arcade, and Shooter): closest matches first, and among equally close ones the better-known games.

Broforce
Shared: Action · Pixel Graphics · 2D

Teenage Mutant Ninja Turtles: Shredder's Revenge
Shared: Action-Adventure · Side Scroller · Arcade

Warhammer 40,000: Boltgun
Shared: Action · Boomer Shooter · Shooter

BlazBlue Entropy Effect
Shared: Action · Action-Adventure · 2D

METAL SLUG
Shared: Action · Arcade · Side Scroller

Huntdown
Shared: Action · Shooter · Side Scroller

SANABI
Shared: Action · Pixel Graphics · Action-Adventure

Skul: The Hero Slayer
Shared: Action · Pixel Graphics · 2D

METAL SLUG 3
Shared: Action · Arcade · Side Scroller

Black Myth: Wukong
Shared: Action · Action-Adventure · Combat

Crimson Desert Enhanced
Shared: Action · Action-Adventure · Fantasy

Terminator 2D: NO FATE
Shared: Action · Side Scroller · Arcade

METAL SLUG X
Shared: Action · Arcade · 2D

Alex Jones: NWO Wars
Shared: Action · Arcade · Shooter

Momodora: Moonlit Farewell
Shared: Action-Adventure · Pixel Graphics · Side Scroller

Blazing Chrome
Shared: Action · Side Scroller · Arcade

BioShock Infinite
Shared: Action · Shooter · Fantasy

SUPER CHICKEN JUMPER
Shared: Arcade · Action-Adventure · 2D

METAL SLUG 2
Shared: Action · Arcade · Side Scroller

Warhammer 40,000: Space Marine 2
Shared: Action · Action-Adventure · PvE

Bloodstained: Curse of the Moon
Shared: Action · Pixel Graphics · Side Scroller

MARVEL Cosmic Invasion
Shared: Arcade · Action · Action-Adventure

Far Cry® 6
Shared: Action-Adventure · Action · Shooter

Exit the Gungeon
Shared: Action · Arcade · 2D